An independent polling group, the Center for Free Elections and Democracy, said Nikolic won 49.4 percent of the vote and Tadic won 47.4 percent. The election results could slow or completely derail the country's efforts to join the European Union.

Tadic conceded to Nikolic and said, "I congratulate him on the victory, it was a fair and well-earned victory and I wish him luck," according to Al Jazeera.

Voter turnout was low, at around 36 percent.

Tadic, who was seeking a final third term in office, billed the election as a referendum on Serbia’s bid to join the EU. Nikolic, who said he supported EU membership for the Balkan nation but not at any cost, centered his campaign on the economy, promising higher taxes on the rich and renewed investments in agriculture and industry, the BBC reports.

A row erupted after the first round of voting on May 6, when pro-Nikolic nationalists accused Tadic’s supporters of falsifying 500,000 votes, although electoral officials and foreign monitors declared the vote to have been fair.

According to the Associated Press, Tadic was slightly ahead of Nikolic in the first round, and was leading the pre-runoff polls. Nikolic’s Serbian Progressive Party won the most votes for parliament, but was thought to be kept out of power due to a deal between Tadic’s Democrats and the third-place Socialists to form the next government together.

The outcome of the vote may affect Serbia’s EU integration prospects and the future of Kosovo, the breakaway Serbian province that declared its independence in February 2008.

Under Tadic, who oversaw Serbia’s EU candidacy negotiations, Bosnian Serb war crimes suspects Radovan Karadzic and General Ratko Mladic were captured and handed over to international prosecutors at The Hague.

The winner of Sunday’s election will have to introduce painful reforms in order to stabilize Serbia’s economy, the Agence France Presse reports. It has one of the highest jobless rates in Europe, with 24 percent of its 7.5 million inhabitants unemployed.

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